Dental apparatus for eliminating wax from molds



Sept. 23, 1930. F. s. MEYER 1,776,267

DENTAL APPARATUS FOR ELIMINATING WAX FROM HOLDS Filed July 2, 1927Patented Sept. 23, 1930 PATENT OFFICE FREDERICK S. MEYER, OFMINNEAPOLIS, MINNESOTA DENTAL APPARATUS FOR ELIMINATING WAX FROM HOLDSApplication filed July 2, 1927.

This invention relates to apparatus and a process for removing oreliminating the wax or plastic model from the mold for casting inlays orcrowns.

In my co-pending application for U. S. Letters Patent entitled Apparatusfor forming molds for crowns and inlays, Serial Number 203,237, filedJuly 2nd, 1927, I disclosed my apparatus, includin an improved crucibleformer, sprue an investment ring, with which I am able to obtainimproved molds for casting gold inlays or crowns. The mold formed by mysaid apparatus has the plastic model enclosed therein and, of course,the material of this model must be removed before the recess in the moldcan be filled with gold.

This invention has for its main object to provide highly efficientapparatus, and a novel process for quickly and efliciently removing theplastic model from the mold,

without subjecting the mold to excessive heat.

1 A further object of my invention is to provide a process for causingthe wax or other plastic material within the mold to be washed out underconsiderable pressure, hot fluid being forced through the porous moldfrom end to end.

Another object of the invention is to provide apparatus comprising acontainer adapted to hold a supply of fluid for removing the plasticmodel and also adapted to retain and clamp the mold and the investmentring in .such manner that said fluid when subjected to heat will bepositively circulated through the investment material of the mold,eliminating all wax or plastic material therein.

Still another object is to provide a-process wherein hot fluid maybeforced under pressure through the investment material of the mold tomelt and carry with it all plastic material constituting the model.

These objects and other objects of the invention will be apparent fromthe following description made in connection with the accompanyingdrawings in which like reference characters refer to similar partsthroughout the several views, and in which:

Serial No. 203,238.

Fig. 1 is a longitudinal section of a preferred embodiment of myeliminating apparatus having an investment ring with a mold thereinattached for elimination of the wax model;

Fig. 2 is a cross section taken on the line 22 of Fig. 1; and

Fig. 3 is an elevation of the investment ring and mold detached, someportions being broken away and others shown in section. As illustrated,my apparatus preferably comprises a generally cylindrical cup member 4closed at its lower end and formin a liquid reservoir 4 in the lowerportlon thereof. A circumferentially disposed inwardly projectingannular flange 5 is provided within cup member 4 disposed directly abovesaid liquid reservoir portion and defining the upper end thereof, saidflange constituting a seat to receive one end of a cylindricalinvestment ring 6 having a mold formed therein for casting an inlay orcrown. The height of the investment ring and mold is greater than thedistance from-the flange 5 to the upper end of cup member 4, whereby oneend of said investment ring will project above said cup member. Theupper portion of my member 4, as shown, is somewhat diminished andprovided with external threads 4 said threads being adapted to engagethe threaded interior of a clamping cap 7. Cap 7 is provided with a topopening 7 a of substantially the diameter of the crucible portion 8 of amold 8. In the type of mold illustrated, the wax model X is covered witha relatively dense inner investment 8 approximately axially disposed inthe investment ring and the investment ring is filled with a less denseouter investment 8. An axial port Y, formed by the sprue in making themold extends from the crucible portion 8 to the wax model.

A washer or packing ring 9 is disposed on the seat formed by flange 5adapted to be engaged by the edge of the investment ring to form an airtight joint between the same and the liquid reservoir 4. Obviously,clamping cap 7 may be screwed down to securely force the investment ring6 against so that there will be little or no opportunity its packedseat. If desired, a washer 10 may be carried in the upper end of the capinterposed between said end and the cruclble end of the investment ring.

. The process employed and the operatlon of my apparatus may be brieflydescribed as follows:

The cup member 4 is first partially filled with water or other desirablel1qu1d to a height slightly above flange 5. Investment rin 6 having themold and wax model X encIosed therein is disposed withm the upperportion of cup 4 engaging at one end the packed seat provided by flange5. Cap 7 1s then inserted over the crucible end of the nvestment ringand is threadedly engaged with the upper end of cup 4 and screwed downto securely clamp the investment rlng agalnst its seat confining theliquid withln reservolr 4. As has been stated, the cup is filled withwater or liquid above the level of flange 5. The joint between the lowerend of the lnvestmentring and flange 5 is water tight and the bottom ofthe mold will be completely sealed by the water, since cup member 4 wasfirst filled above the level of flange 5. S1nce the liquid reservoir 4is especially adapted to hold liquid for the purpose of boiling thesame, it may be properly termed a boiler.

The assembled device with the mold therein is next heated by anysuitable means, as illustrated in Fig. 1, and preferably the heat isdiminished or withdrawn when the water is caused to boil or shortlybefore. The material of the mold is sufliciently orous to permit Waterand steam to be readily forced through it under pressure. The initialheating of the water within the confined reservoir 4 causes a pressureusually sufficient to thoroughly saturate the mold with cool water,

for the mold to absorb the wax. When the water comes to the boilingpoint, steam will, of course, be formed, increasing the pressure uponthe hot water within the reservoir portion 4, steam and hot waterpassing upwardly through the mold and melting and disintegrating the waxand carrying the same out of the upper end of the mold through the spruehole Y. The passage of the hot fluids through the mold continuessufliciently long after the main portion of the wax is carried throughto completely wash away and remove any small deposits of wax left in theminute pores of the mold. The pressure exerted upon the confined waterdue to the action of heat is, of course, considerable, in the embodimentillustrated, attaining from ten to fifteen pounds pressure per squareinch, which I find is adequate for the purpose intended.

.In operation the wax or plastic substance is eliminated very quicklyand the heating is continued gently for a short time thereafter toinsure the mold of being freed of all the compound which constitutes themodel.

My novel process broadly stated, therefore, consists in subjecting oneend of a mold having a Wax or fusible pattern therein to the action ofhot fluid, such as water, and steam under considerable pressure tocompletely remove the pattern'from the opposite end of the mold. Morespecifically my process, therefore, consists in first sub'ecting one endof a mold having a wax mo el therein to a confined supply of Water,heating said confined Water to produce a large amount of pressurethereon, said pressure forcing said confined water and steam generatedthrough the mold to first saturate the same and soften the wax model,said fluids passing out through the other end of said mold and largelythrough the sprue hole between the crucible portion of the mold and thewax model, and serving to loosen, disintegrate and melt the wax modeland carry the pieces thereof through the sprue hole to the crucible.

l/Vith my process and apparatus only a relatively small amount of heatis required to completely remove the wax within the mold since apressure is produced upon the Water even before the water reaches theboiling point and the temperature of the mold itself seldom, if ever,exceeds 212 F., since it is not directly subjected to the heat but isdisposed above the reservoir 4 wherein the liquid is boiling. There can,therefore, be no danger of burning or impairing the mold and all wax orcompound will be removed.

It will, of course, be understood that various changes may be made inthe form, details, proportions and arrangement of the parts withoutdeparting from the scope of the invention.

What is claimed is 1. In apparatus for removing the plastic model from amold, a liquid reservoir having a seat about one end thereof for thereception of a mold, and means for retaining said mold against saidseat.

2. In apparatus for removing the plastic model from a mold, a liquidreservoir of heat conductive material having a seat at one end thereofadapted to receive an investment ring with a mold therein and means forclamping said ring against said seat. I

3. In apparatus for removing the plastic model from a mold, a liquidreservoir having a seat disposed at its upper end adapted to recelve aninvestment ring, packing means upon said seat adapted to cause a watertight joint between one end of said investment ring and said reservoir,and means for clamping sald investment ring against said seat.

4. In apparatus for removing the plastic model from a mold, a cup-likemember having a liquid reservoir in the lower portion thereof, a flangeextending transversely and circumferentially of said member above saidreservoir portion and adapted to receive one end of an investment ring,the lower portion of said ring being telescoped within the upper portionof said cup member, and a pressure cap engaging the crucible end of saidinvest ment ring and having threaded connection -with said cup member toclamp said investsaid plastic model.

6. The process of removing the plastic model from a mold. which consistsin subjecting one end of a mold to the action of confined water andheating said water to cause the same to pass through said mold underpressure and melt and remove the plastic model therewithin through theopposite end thereof.

7. The process of removing the plastic model from a porous mold whichconsists in subjecting a mold to the action of confined water, with thesprue passage disposed outwardly and heating said water to cause thesame to pass through said mold under pressure, softening anddisintegrating and removing the plastic model therewithin through saidsprue passage.

8. In apparatus for removing a plastic model from a mold, a liquidreservoir andmeans for securing a mold within said reservoir to confineliquid therewithin, one surface of said mold being subjected to saidliquid.

9. In apparatus for removing the plastic model from a mold, a liquidreservoir, means within said reservoir for supporting a mold therein.with an end of said mold subjected to the contents of said reservoir,and means for securing said mold against displacement from saidsupporting means.

10. The process of making a mold which consists in embedding a fusiblepattern-in self-hardening material to form a body and subjecting one endof said body to hot fluid under pressure to melt and remove said modelthrough the opposite end of said body.

11. In apparatus for removing the plastic 'model from a mold, a boiler,apair of cooperating clamping elements movable relatively to each other,one of said elements being adapted to engage the end of a mold andhaving communication with said boiler to subject said mold to thedischarge of said boiler.

12. In apparatus for removinga fusible pattern from a mold, a pair ofcooperating clamping elements, movable relatrvely to each other, one ofsaid clamping elements being adapted to engage one end of a mold whichhas embedded therein a fusible pattern, said clamping element alsohaving communication with a source of heated fluid under pressure forcausin said heated fluid to pass through said mol and soften and removesaid pattern through the opposite end of said mold.

13. In apparatus for removing a fusible pattern from a mold, a pair ofcooperating clamping elements movable relatively to each other, one ofsaid elements being adapted to engage one end of an open ended moldcontainer, which contains a mold having a fusible patternembeddedtherein, aseat in saidclamping element forming a sealed jointbetween said end of said mold container and said clamping element andsaid clamping element having communication with a source of heated fluidunder pressure for causing said fluid to pass through said-mold andsoften and remove said pattern from the opposite end of said mold.

14. The process of making a mold which consists in embedding a fusiblepattern in investment material within an open ended member, forming aseal between one end of said open ended member and a source of hot fluidsupply under pressure and passing said hot fluid from said supplythrough said mold by said pressure to soften and remove said fusiblepattern from the opposite end of said mold.

In testimony whereof I aflix my signature.

FREDERICK S. MEYER.

